1. Field of the Invention
The present invention relates to a throttle device for a multipurpose engine, and more particularly relates to a throttle device for a multipurpose engine that is configured such that a throttle valve opens and closes with the aid of an electric motor.
2. Description of the Related Art
In multipurpose engines (spark ignition internal combustion engines) used as drive sources for electrical generators, farming machinery, and various other applications, the opening of the throttle valve is usually adjusted by a mechanical governor made up of a weight and spring, and the rotational speed of the engine is thus controlled.
A technique has recently been proposed for precision control of the rotational speed of an engine using an electronically controlled throttle device (electronic governor) for opening and closing the throttle valve in this type of multipurpose engine with the aid of a stepping motor or other electric motor.
The electric motor for opening and closing the throttle valve is secured with a screw or the like to a fixing component provided near the throttle body. Positioning the electric motor with respect to the fixing component has generally been performed by inserting an extension formed in the electric motor housing into a member such as a hollow boss formed in the fixing component, or by forming a hollow portion in the fixing component that corresponds to the external shape (shape of the housing) of the electric motor and fitting the electric motor into the hollow portion, as taught in Japanese Laid-Open Patent Application No. 2001-263098, for example.